This invention relates to an acoustical membranophone or drum which produces an audible musical sound when struck by an object such as a drum stick. More particularly, this invention relates to a drum in which the tensive and compressive forces associated with tuning and mounting hardware do not restrict the free resonation of the drum shell, and to a bridge which is employed in such a drum. This invention also relates to the manufacture of a snare drum having an improved snare response and a minimum of snare buzz.
Acoustical drums have uniquely influenced history and trace their origin as far back as the Stone Age. Archaeologists have discovered artifacts showing drums in ancient cultures such as Samaria, Mesopotamia, and Babylonia. These artifacts date into the third millennium B.C. Drums have since been used for such diverse purposes as communication and religious ceremonies. In the Fifteenth Century A.D., King Edward VI introduced the drum into the English Army. By the Seventeenth Century, the capture of an enemy's kettledrums signaled that the battle was won. Today, the drum finds a plethora of applications ranging from military marching to the production of orchestral music. Virtually all styles of modern music use drums or an equivalent to keep rhythm.
Drums produce their sound through the striking of a membrane or drum head which has been tightly stretched over a supporting structure such as a drum shell. The drum shell may be of a variety of shapes and is generally cylindrical in nature. Drum shells are usually made from bent wood such as plywood and are typically 3/4 of an inch to over an inch in thickness. Occasionally drums may be made with thinner shells. The bent wood is difficult to form in a precise circle and has a tendency to deform based upon climatic conditions. At a minimum this deformation necessitates retuning and at a maximum necessitates replacement of the drum itself. Depending upon its design, the drum shell may have an end opposite the membrane which is either open, closed, or covered by another similar membrane. When the drum is configured to have a membrane stretched over opposite ends of a tubular drum shell, it is technically referred to as a bimembranophone. More commonly, drums are called tom drums, bass drums, or snare drums.
The membrane was traditionally configured from animal leather which would shrink to fit the drum structure. With this primitive technology, various methods were employed to affix the membrane to an end of the drum structure or bearing edge. The membrane has been: glued to the drum shell, tacked to the drum shell, buttoned to the drum shell, laced to the drum shell, laced to a membrane on the opposite side of the drum shell, and braced to an oppositely positioned membrane. When the membrane is braced, a rigid rim covers the membrane and is tightened for form a brace with a similar, oppositely placed rim.
More recently, the membrane has been manufactured from a thin plastic material having a semi-flexible circular rigid bead mounted on a peripheral edge. The rigid bead is generally made from aluminum and is permanently fastened to the thin plastic material with an epoxy adhesive. The thin plastic material is usually made from mylar.
However, the basic drum design has remained unchanged. The rigid bead is still pulled over the bearing edge at the end of the drum shell and is removably affixed thereto by the rim. The thin plastic membrane is thus formed into a resilient resonant surface.
To hold the rigid bead onto the bearing edge by the rim, various forms of tuning hardware have been employed. The tuning hardware is traditionally affixed to the shell of the instrument. Rigid members, usually made from threaded rod, extend from the rim and are removably fastened into a plurality of metal fasteners incorporated in mounting blocks which are permanently affixed to the drum shell. By tightening the threaded rods into the metal fasteners, a tensive force is applied to the rim and accordingly, across the drum head. The weight of the tuning hardware on the drum shell has the effect of dampening any resonance produced by the drum shell. Additionally, the portion of the drum shell between the tuning hardware and the rim is under a dampening compressive force.
By varying the tensive force applied by each of the metal fasteners, the membrane will vary in tone when struck. Adjustment is commenced until an appropriate tone is achieved. To support the force placed on the tuning hardware, the shell must be made of a sufficient thickness. The ability of the shell to resonate in harmony with the drum head decreases as the thickness of the shell is increased. To achieve a drum shell which will sufficiently support the tuning hardware, it is common to use a drum shell thickness of about 3/4 inch or greater, although thinner shells have been used from time to time with mixed success, and generally these are reinforced at support points. This significantly decreases the amount of shell resonance.
In an alternative method, elongated tension members are fastened between rims which are removably attached to opposite ends of the drum shell. The members may be rigid such as threaded rod, or flexible such as leather lace. The membrane is secured and tuned by tightening the members into the oppositely positioned rims. In the case of the threaded rod, each member is individually tightened or untightened until an appropriate tone is reached. As the rigid members are tightened, a compressive force has the effect of dampening the resonation of the drum shell. Additionally, the drum shell must be made of sufficient thickness such that it will not fracture under the compressive load. The amount of thickness to thwart a fracture is such that the amount of shell resonance is markedly decreased.
Drums of varying size are often combined to form a set. To afford playability and enhance the sound quality, the drums are often mounted above the floor in a close configuration. To hold the drums above the floor they are often affixed to stands or each other by mounting hardware. The mounting hardware is traditionally affixed to the shell of the drum. The drum shell must then be of a sufficient thickness to support the heavy weight of the drum without warping or cracking. This added shell thickness along with the weight of the mounting hardware severely dampens the resonation of the drum shell.
Another type of membranophone, which is strictly a bimembranophone, is the snare drum. The snare drum is a relatively small double membrane drum which is easily carried or placed on a stand. Its diameter is greater than its height or thickness, and snares are added across the bottom membrane. Alternate sides of the bottom of the snare drum are scalloped to form a snare bed. This snare bed reduces the snare buzz.
Snare drums are traditionally made from short tom tom shells. The shells are constructed from bent wood in accordance with traditional drum manufacture. The bent wood is difficult to form in a precise circle and is easily subject to warping due to the tension from the two drum heads and varying climatic variations. Reinforcing hoops are usually placed around the snare drum shell to provide added support.
The snares are grouped in parallel strips across the lower membrane and produce a rattling or reverberating effect when the upper membrane is struck. A snare is a string of spiraled metal which contacts a drum membrane. The correct height adjustment of the snares is difficult to achieve causing the snares to "buzz."